The present invention relates to an apparatus for delivering a flowable substance to a remote location through a conduit, and in particular, but not exclusively, to an apparatus for delivering a lubricant such as grease to the down hole end of, and through, a ground drill.
In the types of down hole drilling where drilling muds are not used for transmitting operational power or torque to a drill drive sub it is desirable to provide a lubricant to minimise friction between the outer circumferential surface of the drill string and the surface of the hole. Reducing the friction reduces the torque and power requirements for the motor driving the drill.
In a non limiting example, in core drilling where torque for drilling is provided by a ground level motor, lubrication is typically achieve in one of two ways. Either drilling mud is pumped through the drill string and forced out the bottom of the down hole end of the drill string back up the hole between the surface of the hole and outer circumferential surface of the drill string. Alternatively, when the string is pulled to change the bit, as the drill pipes forming the drill string are connected together and lowered back into the ground at least the lower most pipes are manually covered in grease to provide the lubrication.
Drilling mud is more expensive per unit volume than grease and therefore from the point of view of cost it is preferred to use grease. However the grease is only applied when the drill string is pulled to change the drill bit and typically this is done as sparingly as possible because tripping the drill can take substantial amounts of time and therefore in itself costs considerable sums of money. In addition, by virtue of the RETRACTABIT ((trademark)) system for in situ replacement of drill bits, the need to trip the drill string to change a drill bit has largely been eliminated. In this instance, if one where to use grease as the lubricant, one would need to trip the drill string simply for the purpose of applying lubricant. Depending on the length of the drill string this may take upwards of 12 hours.
The present invention was developed to provide an apparatus that is capable of delivering a lubricant such as grease to lubricate the outer peripheral/circumferential surface of the drill string while it remains in the ground. However, as will be apparent from the following description, embodiments of the apparatus can deliver any flowable substance to a remote location through any conduit.
According to the present invention there is provided an apparatus for delivering a flowable substance to a remote location through a conduit having an upstream end for insertion of the apparatus, a downstream end provided with an opening, and a stopping means for stopping the apparatus from falling out the downstream end of the conduit, said apparatus comprising at least:
a tubular member for holding a supply of flowable material;
a piston sealingly slidable through the tubular member, the piston initially located upstream of the tubular member; and,
a first valve coupled to a downstream end of the tubular member the first valve having a body provided with at least one orifice and a sealing member slidably mounted on the body and biased to a sealing position in which it seals said at least one orifice;
whereby, in use, said apparatus is inserted in the upstream end of and transported through the conduit where, upon the sealing member abutting the stopping means, fluid pressure is applied to the apparatus through the conduit displacing the sealing member away from the sealing position to unseal any one or more of the at least one orifice and pushing the piston through the tubular member to force the flowable substance through said any one or more of the orifices and out the downstream end of the conduit.
Preferably the seal formed by the piston in the tubular member is arranged to fail when the fluid pressure exerted exceeds a predetermined level so that the fluid exerting the pressure can bypass or otherwise flow through the piston and subsequently flow through any one or more of orifices unsealed by the sealing member and out the downstream end of the conduit.
Preferably the apparatus includes a resilient sealing ring for biasing the sealing member toward the sealing position, the resilient sealing ring disposed about the body of the first valve and adapted to form a first seal between the an outer peripheral surface of the apparatus and an inner surface of the conduit near the downstream end of the conduit when the sealing member is displaced away from the sealing position.
Preferably the body includes a constant diameter portion on which the sealing member is mounted and a contiguous tapered portion having increasing outer diameter in an upstream direction so that when the sealing member is displaced away from the sealing position, the sealing member forces the resilient sealing ring up the tapered portion, radially outwardly expanding the resilient sealing ring into substantial sealing contact between the inner peripheral surface of the conduit and the outer peripheral surface of the apparatus.
Preferably the apparatus further includes fluid flow control means coupled upstream of the tubular member, said fluid flow control means including peripheral sealing means for forming a second seal between the outer peripheral surface of the apparatus and an inner peripheral surface of the conduit upstream of the tubular member thereby directing the fluid exerting the pressure to flow through an opening at the upstream end of the apparatus.
Preferably the fluid flow control means includes a bypass valve at the upstream end of the apparatus movable between a closed position in which the fluid is substantially confined to act directly on the piston, and an open position providing fluid communication between the upstream end of the apparatus, a space formed between the outer peripheral surface of the apparatus and the inner peripheral surface of the conduit downstream of the peripheral sealing means and the opening at the downstream end of the conduit, said bypass valve being operable to switch to the open position when the apparatus is being withdrawn from the conduit.
Preferably the fluid flow control means further includes an outer pipe which is provided with the peripheral sealing means, and the bypass valve includes a hole in the outer pipe and an inner pipe slidable within the outer pipe between a closed location where the inner pipe substantially seals the hole and at an open location where the inner pipe unseals the hole.
Preferably the inner pipe is adapted for connection to means for retrieving the apparatus from the conduit so that when the apparatus is being retrieved, the inner pipe is pulled by the retrieving means to the open location at which position the inner pipe engages the outer pipe to facilitate withdrawal of the whole apparatus from the conduit, and wherein fluid above the apparatus can flow through the bypass valve and out the downstream end of the conduit.
Preferably, the tubular member and piston are constituted as a disposable unit demountably connectable at a downstream end to the valve and at an upstream end to the fluid flow control means.
Preferably said piston includes a passageway extending axially there through and means demountably held in the passageway for initially closing said passageway, said means adapted to be ejected from said passageway to open said passageway when the fluid pressure exceeds said predetermined level to facilitate said failure of said piston.
Preferably said piston is provided with an inner cylindrical body defining the passageway, and wherein the means for initially closing the passageway is a ball.
Preferably the passageway is provided with a recess for snap fitting of said means for initially closing the passageway.
Preferably said apparatus further includes a bypass insert held with said first valve downstream of said piston for spacing said ball from said at least one orifice and maintaining a fluid flow path around said ball to said at least one orifice.